The present invention relates to a self-contained, dimensionally stable matrix for the germination of seeds and the growth of plants and methods of manufacturing them. More particularly, the present invention relates to a dimensionally stable, self-contained hydrophilic plant growth matrix or cohesive mixture having remarkable moisture-holding properties in which seeds may be encapsulated for germination and growth.
Efforts have been made to provide a suitable matrix or "container" for mechanized or automated germination and growth of seedlings and cuttings, particularly in large scale agricultural, horticultural, and reforestation operations. For example, there has been a need to provide automated growing of conifer and hardwood seedlings and outplanting of such seedlings in reforestation in the southern states for at least ten months of the year, as against the present one or two months of outplanting possible with bare root planting, thus making more efficient use of labor and facilities. This is a major problem in that it is necessary to replant at least one billion pine trees a year at present to provide adequate reforestation in the United States of America alone. In addition, at the present time some six billion tabacco seedlings are planted by hand or by semi-automatic methods each year in the United States of America alone. A similar problem exists in other countries and with other plants, for example flowers, vegetables and the like.
One approach to solve this problem has been to provide a wide range of containers, for example, paper tubes, plastic tubes, plastic webbing and plastic tray molds filled with various potting mixtures for seed germination and growth. These have not been entirely satisfactory because, among other reasons, these containers confine the root system within the container in the early stages, which has an effect on future root development and subsequent growth. Particularly, the lack of lateral root growth during the confinement period results in reduced lateral root growth of the seedling when planted in the ground and, hence, minimum lateral support for the tree. Also, these types of containers are relatively expensive and have a relatively high gross weight when filled with potting soil, both wet and dry. Moreover, some plastic tubes fail to split open to permit root emergence and continued growth. In some soils and climates paper tubes disintegrate rapidly, but in others they remain intact after months of planting. The plastic tray molds filled with unconsolidated soil are not suitable for automatic planting in that the plug, when removed, depends entirely upon the root structure and encirclement to hold the soil together.
Another approach to the problem is compressed peat, various molded cubes and the like (Br-8, Kys Kube), but these do not always hold together well and generally contain insufficient supplies of nutrients.
Other efforts to solve the problem of large-scale or automatic commercial plantings have been by providing a foamed plant matrix, such as disclosed in U.S. Pat. Nos. 3,373,009; 2,988,441; and Re 24,820. These foamed matrixes are generally hydrophobic, although some of them are stated to be hydrophilic in that they retain some water. These opencelled foams referred to in the above patents generally do not retain sufficient water for plant growth purposes or perform satisfactorily for proper germination and plant growth.
The present invention is directed to a dimensionally stable, self-contained hydrophilic plant growing matrix which soaks up and retains a relatively large quantity of water, in which water is maintained about the seedling or cuttings for longer periods of time than in other synthetic materials or in such portions of the matrix as may be desirable, in which germination or propagation takes place and growth of the root structure is not confined and lateral root growth is permitted, which is relatively light in weight, both wet and dry, which is economical and which permits automated outplanting of seedlings thus overcoming disadvantages of prior efforts and providing a solution to the problem of largescale commercial planting, reforestation and the like, and methods of making these plant growing matrixes.